Can't get Analog Trigger Working

[TarPista]

Hello!

I'm trying to run one of the sample programs called ''VC_ContAcq_IntClk_AnlgStart' just to see how the analog trigger works. If my understand is correct this program should start the continous acquisition when a rising edge comes on the APFI 0 line (channel 20). I tried to put 5V on ai0 and APFI0 as well, nothing happened. We have a 6251 card, so it should support analog triggering.

Anyway I also tryed to us 'DAQmxCfgAnlgWindowRefTrig' with trigger source as "Dev1/ai0" and it said, that this channel cannot be set to trigger. (Although it is written that analog trigger can occur on AI channels as well.) I am attaching the source code of the sample project.

[MarkJonas]

Hello TarPista,

you are trying to set up a hysteresis trigger. For different trigger types please refer to the M series manual, page 11-4.

http://digital.ni.com/manuals.nsf/websearch/2025C99AB0614F9E8625748000577B9A

For simple testing purposes I would suggest you to use simple analog edge triggering - this will trigger the measurement when the signal reaches some level. To set it up in C code you need to use:

DAQmxSetAnlgEdgeStartTrigSlope

DAQmxSetAnlgEdgeStartTrigLvl

(for reference on this please see the NI-DAQmx C reference help)

Best regards,

Mark 

[TarPista]

Thank you Mark, I'll give it a try!

Best regards,

Zsolt Selmeczi